1. Chapter 12 Carboxylic Acids

2. Chapter 202 Introduction Carbonyl (-C=O) and hydroxyl (-OH) on the same carbon is carboxyl group. Carboxyl group is usually written -COOH. Aliphatic acids have an alkyl group bonded to -COOH. Aromatic acids have an aryl group. Fatty acids are long-chain aliphatic acids.

3. Chapter 203 Common Names Many aliphatic acids have historical names. Positions of substituents on the chain are labeled with Greek letters.

4. Chapter 204 IUPAC Names Remove -e from alkane (or alkene) name, add -oic acid. The carbon of the carboxyl group is #1. 2-chlorobutanoic acid trans-3-phenyl-2-propenoic acid (cinnamic acid)

5. Chapter 205 Naming Cyclic Acids Cycloalkanes bonded to -COOH are named as cycloalkanecarboxylic acids. Aromatic acids are named as benzoic acids. 2- isopropylcyclopentanecarboxylic acid o- hydroxybenzoic acid (salicylic acid)

6. Chapter 206 Dicarboxylic Acids Aliphatic diacids are usually called by their common names (to be memorized). For IUPAC name, number the chain from the end closest to a substituent. Two carboxyl groups on a benzene ring indicate a phthalic acid. 3-bromohexanedioic acid  -bromoadipic acid 1,3-benzenedicarboxylic acid m-phthalic acid

7. Chapter 207 Structure of Carboxyl Carbon is sp 2 hybridized. Bond angles are close to 120 . O-H eclipsed with C=O, to get overlap of  orbital with orbital of lone pair on oxygen.

8. Chapter 208 Boiling Points Higher boiling points than similar alcohols, due to dimer formation. Acetic acid, b.p. 118  C

9. Chapter 209 Melting Points Aliphatic acids with more than 8 carbons are solids at room temperature. Double bonds (especially cis) lower the melting point. Note these 18-C acids: – Stearic acid (saturated): 72  C – Oleic acid (one cis double bond): 16  C – Linoleic acid (two cis double bonds): -5  C

10. Chapter 2010 Solubility Water solubility decreases with the length of the carbon chain. Up to 4 carbons, acid is miscible in water. More soluble in alcohol. Also soluble in relatively nonpolar solvents like chloroform because it dissolves as a dimer.

11. Chapter 2011 Acidity

12. Chapter 2012 Resonance Stabilization

13. Chapter 2013 Substituent Effects on Acidity

14. Chapter 2014 Salts of Carboxylic Acids Sodium hydroxide removes a proton to form the salt. Adding a strong acid, like HCl, regenerates the carboxylic acid.

15. Chapter 2015 Naming Acid Salts Name the cation. Then name the anion by replacing the -ic acid with -ate. potassium 3-chloropentanoate potassium  -chlorovalerate

16. Chapter 2016 Properties of Acid Salts Usually solids with no odor. Carboxylate salts of Na +, K +, Li +, and NH 4 + are soluble in water. Soap is the soluble sodium salt of a long chain fatty acid. Salts can be formed by the reaction of an acid with NaHCO 3, releasing CO 2.

17. Chapter 2017 Purifying an Acid

18. Chapter 2018 Some Important Acids Acetic acid is in vinegar and other foods, used industrially as solvent, catalyst, and reagent for synthesis. Fatty acids from fats and oils. Benzoic acid in drugs, preservatives. Adipic acid used to make nylon 66. Phthalic acid used to make polyesters.

19. Chapter 2019 Synthesis Review Oxidation of primary alcohols and aldehydes with chromic acid. Cleavage of an alkene with hot KMnO 4 produces a carboxylic acid if there is a hydrogen on the double-bonded carbon. Cleavage of an alkyne with ozone or hot permanganate.

20. Chapter 2020 Fischer Esterification Acid + alcohol yields ester + water. Acid catalyzed for weak nucleophile. All steps are reversible. Reaction reaches equilibrium.

21. Chapter 2021 Amides from Acids Amine (base) removes a proton from the carboxylic acid to form a salt. Heating the salt above 100  C drives off steam and forms the amide.

22. Chapter 2022 Reduction to 1  Alcohols Use strong reducing agent, LiAlH 4. Borane, BH 3 in THF, reduces carboxylic acid to alcohol, but does not reduce ketone.

23. Chapter 2023 Reduction to Aldehyde Difficult to stop reduction at aldehyde. Use a more reactive form of the acid (an acid chloride) and a weaker reducing agent, lithium aluminum tri(t-butoxy)hydride.

24. Chapter 2024 Esters from Acid Chlorides Acid chlorides react with alcohols to give esters in good yield. Mechanism is nucleophilic addition of the alcohol to the carbonyl as chloride ion leaves, then deprotonation.

25. Chapter 2025 End of Chapter 12